The present invention relates to an organic solvent type thermosetting coating composition capable of forming a rigid coating film having a Tukon hardness (20xc2x0 C.) of at least 25, excellent in stain resistance, and from which pollutants can easily be removed even when they are adhered, and further relates to a method to form a multilayered topcoating film with use of said coating composition.
As a topcoat paint (in particular clear paint) for automobile body panel, there are usually used organic solvent type paints which comprise, as main components, hydroxyl group-containing acrylic resin and melamine resin. Although good in weatherability, finished appearance, etc., a coating film made from these paints has yet to have sufficient xe2x80x9cacid rain resistancexe2x80x9d which has been high-lighted recently. As a topcoat paint which has improved in this acid rain resistance, there have been proposed organic solvent type paints (generally called acid epoxy type paints) which comprise, as main components, carboxyl group-containing resin and epoxy group-containing resin, and which are free of melamine resin. Although excellent in weatherability and finished appearance and also in acid rain resistance, a cured film formed from said acid epoxy type paints has a problem of poor stain resistance which makes it difficult to remove adhered pollutants tracelessly.
The surface of top coating film on outer body panel of automobile which is mostly used outdoors is apt to be stained with pollutants (e.g., bird droppings, pollens, dead insects etc.), iron powder, sand mud, exhaust soot (carbon, paraffin, etc.) which adhere to, soak or sink into said coating film. For example, bird droppings which have stuck on the coating film condense as they are dried and solidified, with the result that the surface of top coating film shrinks together, causing decrease in the appearance of portions concerned, such as gloss and distinctness-of-image-gloss. When wetted with rain etc., pollens and dead insects which have adhered to the coat surface elute protein or amino acid, which may possibly penetrate into the coating film to cause stains. Iron powder, sand mud, exhaust soot etc. also adhere to, or sink into coating film to cause stains.
Automobile body panel, when left outdoors, may raise its temperature to 60xc2x0 C. or higher by solar heat. Top coating film is softened at such a high temperature, and, thus, staining by the above-mentioned causes becomes more likely to be accelerated.
Once a coating film is stained in such a manner, the stains cannot be removed by simply wiping or using cleanser or wax, and, thus, appearance is damaged.
Thus, the main purpose of the present invention is to provide a novel organic solvent type paint capable of forming a coating film which is equivalent or superior, in weatherability, finished appearance, acid resistance, etc., to coating film of conventional organic solvent type paints (e.g., those which comprise, as main components, acrylic resin and melamine resin, such as acid epoxy type paints) used as an automobile topcoat paint, and which is also good in stain resistance.
As a result of assiduous study with a view to achieving the above-mentioned purpose, inventors of the present invention have found out that an organic solvent type thermosetting paint which contains a compound having alicyclic epoxy group, a secondary amino group-containing compound and a thermally latent cationically polymerizable catalyst, and, if necessary, colloidal silica as well, gives a coating film which is excellent in crosslinking curing reactivity, and which, once cured, is rigid and hardly softened even when exposed to a temperature of 60xc2x0 C. or higher, does not allow pollutants to soak or sink into, can easily be freed from pollutants, even though they have stuck, by water washing or dry cloth rubbing without using deter-gents, and, further, is also excellent in weatherability, finished appearance, acid resistance, etc., and thus have completed the present invention.
Thus, the present invention provides an organic solvent type thermosetting paint (hereinafter referred to as xe2x80x9cthe paint of the present inventionxe2x80x9d) which is characterized by containing (A) a compound with a number-average molecular weight of less than 2000 and having at least two alicyclic epoxy groups in a molecule, (B) a secondary amino group-containing compound and (C) a thermally latent cationically polymerizable catalyst, and, if necessary, (D) colloidal silica as well.
The present invention further provides a coating method (hereinafter referred to as xe2x80x9cthe coating method of the present inventionxe2x80x9d) which is characterized in that, in a method for forming a multilayered top coating film by coating a substrate with at least one colored paint and at least one clear paint in order, the paint of the present invention is used as a clear paint which is to be uppermost applied.
The paint of the present invention is capable of forming a cured coating film which has a Tukon hardness (20xc2x0 C.) of at least 25, a breaking stress of at least 500 kg/cm2 and a Young""s modulus of at least 20000 kg/cm2. A coating film having these property values is more rigid and tough than film of conventional paints, is hardly softened even when exposed to a temperature of 60xc2x0 C. or higher, does not allow pollutants to soak or sink into, and can easily be freed from pollutants even though they have stuck, and thus has markedly improved stain resistance.
In this description, xe2x80x9cTukon hardness (20xc2x0 C.)xe2x80x9d value is obtained as follows. A paint is applied on a glass plate so that the cured coating film may have a thickness of 30 xcexcm, and is then heated under a certain condition, for example, at 140xc2x0 C. for 30 minutes. Thus cured coating film is measured at 20xc2x0 C. by a TUKON microhardness tester made by American Chain and Cable Company. The larger the value is, the harder is the film. A cured coating film which is formed from known thermosetting paints has usually a Tukon hardness of about 5 to 10. It would be understood therefore how hard a cured film with a Tukon hardness (20xc2x0 C.) of at least 25 which can be formed by the paint of the present invention is.
xe2x80x9cBreaking stressxe2x80x9d value is obtained as follows. A paint is applied on a glass plate so that the cured coating film may have a thickness of 30 xcexcm, and is then heated under a certain condition, for example, at 140xc2x0 C. for 30 minutes. Thus cured coating film is peeled off the glass plate, and is measured at 20xc2x0 C. by a tensilon meter made by Orientech Corporation. The larger the value is, the higher the strength of the coating film. A cured coating film which is formed from known thermosetting paints has usually a breaking stress of about 300 to 500 kg/cm2. Hence, a coating film with a breaking stress of at least 500 kg/cm2, which can be formed by using the paint of the present invention has a higher breaking stress and is more tough than coating film formed from conventional thermosetting paints.
xe2x80x9cYoung""s modulusxe2x80x9d is a value which is measured in a manner similar to the above-mentioned breaking stress. The larger the value is, the higher is the hardness of coating film. A cured coating film which is formed from known thermosetting paints has usually a Young""s modulus of about 10000 to 20000 kg/cm2. Hence, a coating film with a Young""s modulus of at least 20000 kg/cm2, which can be formed by using the paint of the present invention is more rigid than coating film formed from conventional thermosetting paints.
The paint and coating method of the present invention are described in more detail below.
The paint of the present invention is an organic solvent type thermosetting paint which is characterized by comprising (A) a compound with a number-average molecular weight of less than 2000 and having at least two alicyclic epoxy groups in a molecule, (B) a secondary amino group-containing compound and (C) a thermally latent cationically polymerizable catalyst, and, if necessary, (D) colloidal silica as well.
xe2x80x9cAlicyclic epoxy groupxe2x80x9d means an oxirane ring (a 3-membered ring constituted by two carbon atoms and an oxygen atom) formed by two adjacent carbon atoms, which constitute a ring of alicyclic hydrocarbon, and by an oxygen atom, and includes neither spiro-type epoxy groups in which the alicyclic hydrocarbon ring and the oxirane ring has only a single carbon atom in common, nor epoxy groups in which an alicyclic hydrocarbon ring and an oxirane ring are connected via another carbon atom. Said alicyclic hydrocarbon can usually be constituted by three to 12, preferably five to six cyclic carbon atoms.
Component (A) is a compound which has 2 or more, preferably 2 to 3, of such alicyclic epoxy groups in a molecule, and which has a number-average molecular weight of less than 2000, preferably 100 to 1500. In general, component (A) has preferably an average epoxy equivalent of 50 to 500, in particular 100 to 300.
Examples of such component (A) include dicyclopentadiene dioxide, bis(2,3-epoxycyclopentyl) ether, epoxycyclohexenecarboxylic acid ethylene glycol diester, bis(3,4-epoxycyclohexylmethyl) adipate, bis(4,5-epoxy-2-methylcyclohexylmethyl) adipate, ethylene glycol-bis(3,4-epoxycyclohexanecarboxylate), 3xe2x80x2,4xe2x80x2-epoxycyclohexylmethyl-3,4-epoxycyclo-hexanecarboxylate, 3,4-epoxy-6-methylcyclohexyl-methyl-3,4-epoxy-6-methylcyclohexanecarboxylate, 1,2,5,6-diepoxy-4,7-methanoperhydroindene, 2-(3,4-epoxycyclohexyl)-3xe2x80x2,4xe2x80x2-epoxy-1,3-dioxane-5-spirocyclohexane, 1,2-ethylenedioxy-bis(3,4-epoxycyclohexylmethane), di-2,3-epoxycyclopentyl ether, 4xe2x80x2,5xe2x80x2-epoxy-2xe2x80x2-methylcyclohexylmethyl-4,5-epoxy-2-methylcyclohexanecarboxylate, etc.
A compound which ontains one or more, preferably one, secondary amino group. xe2x80x9cSecondary amino groupxe2x80x9d means an amino group (xe2x80x94NHR; R is an organic group such as alkyl group, hydroxyalkyl group, etc.) which has one active hydrogen directly bonded to amino nitrogen. Examples of such a secondary amino group-containing compound include dialkylamine such as dimethylamine, diethylamine, diisopropylamine, dibutylamine; alkanolamine such as diethanolamine, dipropanolamine, di(2-hydroxypropyl)amine, monomethylaminoethanol, N-ethylethanolamine; polyamine such as hydroxyethylaminoethylamine, ethylaminoethylamine, methylaminopropylamine; cyclic amine such as ethyleneimine (aziridine), propyleneimine, piperazine, morpholine. Among them, a compound such as alkanolamine which has both a secondary amino group and a hydroxyl group in a molecule is preferably used since it accelerates the curing reactivity of component (A) to form a more rigid coating film.
Such component (B) which is used for the paint of the present invention has a molecular weight which is preferably at most about 400, in particular in the range of 200 to 400.
The thermally latent cationically polymerizable catalyst (C) which is used for the paint of the present invention is a compound which, although inactive at room temperature, has an action of cleaving to generate cation when heated to reach critical temperature and thus initiating cationic polymerization. Examples of this component (C) include onium salt of nitrogen, sulfur, phosphorus or iodine each of which has SbF6xe2x88x92, BF4xe2x88x92, AsF6xe2x88x92, PF6xe2x88x92 as an anionic component. Concretely preferred compounds are as follows:
i) Quaternary Ammonium Salt Type Compounds:
For example, N,N-dimethyl-N-benzylanilinium antimony hexafluoride, N,N-diethyl-N-benzylanilinium boron tetrafluoride, N,N-dimethyl-N-benzylpyridinium antimony hexafluoride, N,N-diethyl-N-benzylpyridinium trifluoromethanesulfonate, N,N-di-methyl-N-(4-methoxybenzyl)pyridinium antimony hexafluoride, N,N-diethyl-N-(4-methoxybenzyl)pyridinium antimony hexafluoride, N,N-diethyl-N-(4-methoxybenzyl)toluidinium antimony hexafluoride, N-xcex1,xcex1-dimethylbenzylpyridinium hexafluoroantimonate, N,N-di-methyl-N-(4-methoxybenzyl)toluidinium antimony hexafluoride.
ii) Sulfonium Salt Type Compounds:
For example, triphenylsulfonium boron tetrafluoride, triphenylsulfonium antimony hexafluoride, triphenylsulfonium arsenic hexafluoride, Adeka CP-66(copyright) (made by Asahi Denka Kogyo K. K.), Adeka CP-77(copyright) (made by Asahi Denka Kogyo K. K.), tri(4-methoxyphenyl)sulfonium arsenic hexafluoride, benzyltetramethylene-sulfonium hexafluoroantimonate, diphenyl(4-phenylthiophenyl)-sulfonium arsenic hexafluoride.
iii) Phosphonium Salt Type Compounds:
For example, ethyltriphenylphosphonium antimony hexafluoride, tetrabutylphosphonium antimony hexafluoride.
iv) lodonium Salt Type Compounds:
For example, diphenyliodonium arsenic hexafluoride, di-4-chlorophenyliodonium arsenic hexafluoride, di-4-bromophenyliodonium arsenic hexafluoride, di-p-tolyliodonium arsenic hexafluoride, phenyl(4-methoxyphenyl)iodonium arsenic hexafluoride.
These cationically polymerizable catalysts (C) have a function of cleaving to generate cation when heated to reach critical temperature (for example, about 100 to 180xc2x0 C., preferably about 120 to 160xc2x0 C.) for about 10 to 40 minutes, and thus initiating cationic polymerization on the basis of the alicyclic epoxy group of the component (A), and accelerating the crosslinking reaction and three-dimensional curing of component (A).
As colloidal silica which is optionally blended in the paint of the present invention, any known ones can be used. Specifically preferable one is in the form of dispersion of ultrafine particles of silicon dioxide (SiO2) suspended in an organic solvent. Said ultrafine particles are preferably of spheric silica which have been rendered high molecular by siloxane bond and which may have hydroxyl groups on their surface. The size of said fine particles is preferably in the range of 2 to 100 nm, in particular 5 to 50 nm.
As organic solvent to suspend these ultrafine particles, any solvent can be used with no particular restriction. Examples of solvent include hydrocarbon type one such as hexane, heptane, xylene, toluene, cyclohexane; ester type one such as methyl acetate, ethyl acetate, acetic acid ethylene glycol monomethyl ether, acetic acid diethylene glycol monomethyl ether; ether type one such as isopropyl ether, ethylene glycol monomethyl ether, diethylene glycol monobutyl ether; alcohol type one such as ethyl alcohol, butyl alcohol, hexyl alcohol; ketone type such as methyl isobutyl ketone, methyl ethyl ketone, isophorone, acetophenone.
In the dispersion of ultrafine particles of silicon dioxide (SiO2) suspended in an organic solvent, the content of said silicon dioxide ultrafine particles is, in general, preferably in the range of 15 to 50% by weight, in particular 20 to 43% by weight.
The dispersion of ultrafine particles of silicon dioxide (SiO2) suspended in an organic solvent, usable in the paint of the present invention, can be obtained on the market. Examples of such a dispersion include Snowtex MA-ST-M(copyright), IPA-ST(copyright), EG-ST(copyright), EG-ST-ZL(copyright), NPC-ST(copyright), DMAC-ST(copyright), MEK(copyright), XBA-ST(copyright) and MIBK-ST(copyright) (all of which are trademarks of products of Nissan Chemical Industires Co., Ltd.).
Paint of the Present Invention
The paint of the present invention is an organic solvent type thermosetting paint comprising above-mentioned component (A), component (B) and component (C), and, if necessary, component (D) as well. The blending ratio of these components is not particularly restricted but can be selected optionally according to the purpose of use of paint etc. Generally, however, 0.1 to 1 part by weight, particularly 0.3 to 1 part by weight, more desirably 0.5 to 1 part by weight of component (B), 0.05 to 10 parts by weight, particularly 0.25 to 7.5 parts by weight, more desirably 0.5 to 5 parts by weight of component (C), and 10 to 140 parts by weight, particularly 15 to 100 parts by weight, more desirably 20 to 60 parts by weight of component (D) are preferably used per 100 parts by weight of the solid content of component (A).
The paint of the present invention can be prepared, for example, by blending the above-mentioned component (A), component (B) and component (C), and, if necessary, component (D) as well in an organic solvent. Examples of usable organic solvent include toluene, xylene, ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone, methanol, ethanol, butanol, carbinol acetate, methoxybutyl acetate, cellosolve, cellosolve acetate, which are however not restrictive.
According to the purpose of use of the paint, usual paint additives such as coloring pigment, iridescent pigment, metallic pigment, extender pigment, ultraviolet absorbent, light stabilizer, fluidity modifier, cissing inhibitor as well as the above-mentioned components may be blended in the paint of the present invention.
The paint of the present invention may be used as solid color paint, metallic paint or iridescent paint. However, since this paint forms a coating film excellent in stain resistance, it is most preferably used as a clear paint with a view to forming the upper-most transparent coating film of a multilayered coating film. For example, the paint of the present invention can be used as the upper-most clear paint in a method of coating a substrate such as automobile body panel with one or more kind of coloring paint and one or more kind of clear paint in order, so as to form a multilayered top coating film.
The present invention thus provides also a method of forming a multilayered top coating film by coating a substrate such as automobile body panel with one or more kind of coloring paint and one or more kind of clear paint successively, which method is characterized by using the paint of the present invention as clear paint to be applied uppermost.
The Coating Method of the Present Invention
The coating method of the present invention is concretely carried out, for example, by the following processes a-c, which are however not restrictive.
The coloring paint used in the xe2x80x9cprocess axe2x80x9d includes solid color paint, metallic paint and iridescent paint. For this coloring paint, there may be used known thermosetting paints which contain resin component, coloring pigment and solvent.
The resin component used in the above-mentioned coloring paint concretely comprises one or more species of base resin component which are selected from acrylic resin, vinyl resin, polyester resin, alkyd resin, urethane resin, etc. having a crosslinking functional group (e.g., hydroxyl group, epoxy group, carboxyl group, alkoxysilane group), and one or more species of crosslinking agent component to crosslink and cure said base resin component which are selected from alkyl-etherified melamine resin, urea resin, guanamine resin, polyisocyanate compound which may be blocked, epoxy compound, carboxyl group-containing compound etc. These two components are preferably used in the ratio of 50 to 90%, particularly 60 to 85% of the base resin component, and 50 to 10%, particularly 40 to 15% of the crosslinking agent component, based on the total weight.
Coloring pigment includes solid color pigment, metallic pigment and iridescent pigment, which may be used either singly or in combination of two or more of them. As for solvent, although organic solvent type is suitably used, aqueous type may also be used.
xe2x80x9cProcess axe2x80x9d is suitably conducted by 2-coat- 1-bake process (2C1B) or 2-coat-2-bake process (2C2B) in the following manner: Metal-made or plastic-made automobile substrate is coated with the above-mentioned coloring paint either directly or after said substrate has been coated with primer such as cationically electrodepositable paint and, as need be, further with an intermediate paint and cured. Said coloring paint is applied with airless spray, air spray or electro-static coating so that cured film may have a thickness of about 10 to bout 50 xcexcm, and is then either heated at about 100 to about 180xc2x0 C., referably about 120 to about 160xc2x0 C., for about 10 to about 40 minutes to be crosslinked and cured, or left to stand still at room temperature for several minutes without curing treatment. Then, a clear paint comprising the paint of the present invention is applied in a similar manner so that cured film may have a thickness of about 20 to about 70 xcexcm, and is then heated at about 100 to about 180xc2x0 C., preferably about 120 to about 160xc2x0 C., for about 10 to about 40 minutes to be crosslinked and cured.
As a coloring paint used in this process b, a paint selected from solid color paint, metallic paint and iridescent paint which are described in the above xe2x80x9cprocess axe2x80x9d can be used. First clear paint is a paint for forming a transparent coating film. Either a paint obtained by eliminating most or all of coloring pigment from the above-mentioned coloring paint or the paint of the present invention is usable as this first clear paint. As second clear paint, the paint of the present invention is used.
xe2x80x9cProcess bxe2x80x9d is suitably conducted by 3-coat-1-bake process (3C1B), 3-coat-2-bake process (3C2B) or 3-coat-3-bake process (3C3B) in the following manner: Metal-made or plastic-made automobile substrate is coated with the above-mentioned coloring paint either directly or after said substrate has been coated with primer such as cationically electrodepositable paint and, as need be, further with an intermediate paint and cured. Said coloring paint is applied with airless spray, air spray or electrostatic coating so that cured film may have a thickness of about 10 to about 50 xcexcm, and is then either heated at about 100 to about 180xc2x0 C., preferably about 120 to about 160xc2x0 C., for about 10 to about 40 minutes to be crosslinked and cured, or left to stand still at room temperature for several minutes without curing treatment. Then, the coated surface is coated with first clear paint in a similar manner so that so that cured film may have a thickness of about 10 to about 50 xcexcm, and is then either heated at about 100 to about 180xc2x0 C., preferably about 120 to about 160xc2x0 C., for about 10 to about 40 minutes to be crosslinked and cured, or left to stand still at room temperature for several minutes without curing treatment. Then, the paint of the present invention as the second clear paint is applied in a similar manner so that cured film may have a thickness of about 10 to about 50 xcexcm, and is then heated at about 100 to about 180xc2x0 C., preferably about 120 to about 160xc2x0 C., for about 10 to about 40 minutes to be crosslinked and cured.
As a first coloring paint used in this xe2x80x9cprocess cxe2x80x9d, a paint selected from solid color paint, metallic paint and iridescent paint which are described in the above xe2x80x9cprocess axe2x80x9d can be used. Particularly preferred are solid color paint and metallic paint which form a coating film which is non-transparent and hides substrate. A second coloring paint is a paint to be applied on the coated surface of the first coloring paint. Although the same coloring paint as described in the above xe2x80x9cprocess axe2x80x9d is usable, it is desirable that the second coloring paint should have a hiding power to such an extent that the color tone (solid color, metallic feeling, light interference pattern, etc.) of the coated surface of the first coloring paint can be visually recognized through the coating film of the second coloring paint. It is therefore preferable that the amount of solid color pigment, metallic pigment or iridescent pigment blended in the second coloring paint is smaller than in the first coloring paint. Clear paint is a paint to form a transparent coating film. The paint of the present invention can be used as a clear paint.
xe2x80x9cProcess cxe2x80x9d is suitably conducted by 3C1B, 3C2B or 3C3B in the following manner: Metal-made or plastic-made automobile substrate is coated with the first coloring paint either directly or after said substrate has been coated with primer such as cationically electrodepositable paint and, as need be, further with an intermediate paint and cured. Said first coloring paint is applied with airless spray, air spray or electrostatic coating so that cured film may have a thickness of about 10 to about 50 xcexcm, and is then either heated at about 100 to about 180xc2x0 C., preferably about 120 to about 160xc2x0 C., for about 10 to about 40 minutes to be crosslinked and cured, or left to stand still at room temperature for several minutes without curing treatment. Then, the surface of thus applied first coloring paint is coated with second coloring paint in a similar manner so that so that cured film may have a thickness of about 10 to about 50 xcexcm, and is then either heated at about 100 to about 180xc2x0 C., preferably about 120 to about 160xc2x0 C., for about 10 to about 40 minutes to be crosslinked and cured, or left to stand still at room temperature for several minutes without curing treatment. Then, the paint of the present invention as a clear paint is applied in a similar manner so that cured film may have a thickness of about 10 to about 50 xcexcm, and is then heated at about 100 to about 180xc2x0 C., preferably about 120 to about 160xc2x0 C., for about 10 to about 40 minutes to be crosslinked and cured.
The afore-mentioned paint and coating method of the present invention show the following effects:
(1) Having no particular need of blending high molecular weight components, the paint of the present invention has good atomization property even though the solid content in the paint, when applied with airless spray, air spray, electrostatic coating, etc., is high (for example, at least 60% by weight, preferably 65 to 80% by weight), with the result that obtained coated surface has excellent smoothness.
(2) The cured coating film formed from the paint of the present invention is equivalent or superior, in weatherability, finished appearance, etc., to a coating film of organic solvent type paint comprising, as main components, hydroxyl group-containing acrylic resin and melamine resin, and, moreover, is remarkably excellent in acid resistance.
(3) The cured coating film formed from the paint of the present invention is equivalent or superior, in acid resistance, weatherability and finished appearance, to a coating film of acid epoxy type paint comprising, as main components, carboxyl group-containing resin and epoxy group-containing resin, and, moreover, is remarkably excellent in stain resistance.
(4) The paint of the present invention is capable of forming a cured coating film which has a Tukon hardness (20xc2x0 C.) of at least 25, preferably 30 to 40, a breaking stress of at least 500 kg/cm2, preferably 600 to 800 kg/cm2, and a Young""s modulus of at least 20000 kg/cm2, preferably 23000 to 28000 kg/cm2. A coating film having these property values is more rigid and tough than film of conventional paints, is hardly softened even when exposed to a temperature of 60xc2x0 C. or higher, does not allow pollutants to soak or sink into, is capable of inhibiting the promotion of staining, and can easily be freed from pollutants, and thus has markedly improved stain resistance.
(5) Since the cured coating film formed from the paint of the present invention is super-rigid, pollutants (for example, bird droppings, pollens, dead insects), stain-causing substances such as iron powder, sand mud, exhaust soot (carbon, paraffin, etc.) are hard to adhere to the film, and, even though adhered, said substances scarcely soak or sink in the coating film, and are easily wiped away. Hence, gloss and distinctness-of-image-gloss of the portions concerned do not decrease.
(6) Since the cured coating film formed from the paint of the present invention is super-rigid, stuck stains can be easily removed by simply wiping or simple water washing with sponge without using detergent or wax.
(7) The multilayered coating film formed by the method of the present invention is excellent in weatherability, finished appearance such as gloss and distinctness-of-image-gloss, and also in acid resistance and stain resistance.